The invention provides novel tetradentate enediyne ligands that are themselves thermally stable, yet react at about room temperature or slightly higher upon addition of metal ions or under photothermal conditions. In another aspect of the invention, a method of treating a disorder in a mammal comprising administering a therapeutically effective amount of a compound or composition is provided. In addition, the free ligand can be delivered to the mammal prior to complexation to metals, such that the ligand is exposed to a metal in the body and forms a metal complex in vivo. Furthermore, a metal complex of the invention can be administered to the mammal such that the complex exchanges the first metal center with another endogenous metal in order to form a second metal complex in vivo. The second metal complex is capable of forming a benzenoid diradical under physiological conditions and/or under photothermal conditions.